Method of electoless deposition of thin metal and dielectric films with temperature controlled on stages of film growth

ABSTRACT

The method of the invention comprises accumulating experimental data or obtaining existing data with regard to the optimal time-temperature relationship of the deposition process on various film-formation stages for various materials, forming nuclei of a selected material on the surface of the treated object in the first stage under first temperature-controlled conditions for the formation of nuclei of said selected material, converting the nuclei of the aforementioned selected material into island-structured deposited layer of said material by causing lateral growth of the nuclei under second temperature-controlled conditions; converting the island-structure layer into a continuously interconnected cluster structure by causing further lateral growth of said island-structured deposited layer under third temperature-controlled conditions; forming a first continuous film of said material under fourth temperature controlled conditions which provides said first continuous film with predetermined properties; and then completing the formation of a final coating film by growing at least one subsequent continuous film of said material under fifth temperature-controlled conditions until a film of a predetermined thickness is obtained. The fifth temperature-controlled conditions may be characterized by a pulse-mode or step-like variations of temperature in time with rapid cooling or heating for obtaining high degree of crystallinity or for increase in the rate of deposition. The method of the invention could be realized with the use of the electroless deposition apparatus with instantaneous cooling or heating of the object, e.g., a semiconductor substrate, in a deposition chamber.

FIELD OF THE INVENTION

[0001] The invention relates to the formation of thin films on surfacesof objects, more particularly to electroless deposition of very thinmetal or dielectric films on substrates. The method and apparatus of theinvention may find application in the manufacture of semiconductordevices, in particular integrated circuits.

BACKGROUND OF THE INVENTION

[0002] Manufacturing of semiconductor devices, in particular integratedcircuits having multiple-layered structures with various metal andnon-metal layers laminated on a semiconductor substrate, typicallyinvolves application of several metal layers onto a substrate or ontoother previously deposited layers. These layers may have a complicatedplanar topology since these layers may constitute thousands ofindividual devices, which in combination form an integrated circuit orso-called “chip”. Modern chips may have metal or dielectric layers withthickness from tens of Angstroms to fractions of a micron.

[0003] It is understood that thin metallic films used in integratedcircuits of semiconductor devices function as conductors of electriccurrent. Furthermore, it is known that densities of signal currents inmetallic interconnections used in integrated circuit may reach extremelyhigh values that generate such phenomena as electromigration associatedwith spatial transfer of mass of conductor films. Therefore thecharacteristics and properties of the deposited metal films (uniformityof film thickness, low electrical resistivity, etc.) determineperformance characteristics and quality of the integrated circuit and ofthe semiconductor device as a whole.

[0004] In view of the above, thin metal films used in the integratedcircuits should satisfy very strict technical requirements relating tometal deposition processes, as well as to repeatability andcontrollability of the aforementioned processes.

[0005] A wide range of metals is utilized in the microelectronicmanufacturing industry for the formation of integrated circuits. Thesemetals include, for example, nickel, tungsten, platinum, copper, cobalt,as well as alloys of electrically conductive compounds such assilicides, solders, etc. It is also known that coating films are appliedonto substrates with the use of a variety of technological processessuch chemical vapor deposition (CVD), physical vapor deposition (PVD),electroplating, and electroless plating. Of these techniques,electroplating and electroless plating or deposition tend to be the mosteconomical and most promising for improvement in characteristics of thedeposited films. Therefore, electroplating and electroless platingtechniques successfully replaces other technologies.

[0006] Electroplating and electroless plating can be used for thedeposition of continuous metal layers as well as patterned metal layers.One of the process sequences used by the microelectronic manufacturingindustry to deposit metals onto semiconductor wafers is known to as“damascene” processing. In such processing, holes, commonly called“vias”, trenches and/or other recesses are formed on a workpiece andfilled with a metal, such as copper. In the damascene process, thewafer, with vias and trenches etched in the dielectric material, isfirst provided with a metallic seed layer, which is used to conductelectrical current during a subsequent metal electroplating step. If ametal such as copper is used, the seed layer is disposed over a barrierlayer material, such as Ti, TiN, etc. The seed layer is a very thinlayer of metal, which can be applied using one or more processes. Forexample, the seed layer of metal can be laid down using physical vapordeposition or chemical vapor deposition processes to produce a layerwith the thickness on the order of 1,000 Angstroms. The seed layer canadvantageously be formed of copper, gold, nickel, palladium, or othermetals. The seed layer is formed over a surface, which may contain vias,trenches, or other recessed device features.

[0007] A metal layer is then electroplated onto the seed layer in theform of a continuous layer. The continuous layer is plated to form anoverlying layer, with the goal of providing a metal layer that fills thetrenches and vias and extends a certain amount above these features.Such a continuous layer will typically have a thickness on the order of5,000 to 15,000 Angstroms (0.5-1.5 microns).

[0008] After the continuous layer has been electroplated onto thesemiconductor wafer, excess metal material present outside of the vias,trenches, or other recesses is removed. The metal is removed to providea resulting pattern of metal layer in the semiconductor integratedcircuit being formed. The excess plated material can be removed, forexample, using chemical mechanical planarization. Chemical mechanicalplanarization is a processing step, which uses the combined action ofchemical removal agents, or a chemical removal agents with an abrasive,which grinds and polishes the exposed metal surface to remove undesiredparts of the metal layer applied in the electroplating step.

[0009] Disadvantages associated with electroplating are technicalproblems in connection with designing of reactors used in theelectroplating of semiconductor wafers. Utilization of a limited numberof discrete electrical contacts (e.g., 8 contacts) with the seed layerabout the perimeter of the wafer ordinarily produces higher currentdensities near the contact points than at other portions of the wafer.This non-uniform distribution of current across the wafer, in turn,causes non-uniform deposition of the plated metallic material. Currentthieving, affected by the provision of electrically conductive elementsother than those, which contact the seed layer, can be employed near thewafer contacts to minimize such non-uniformity. But such thievingtechniques add to the complexity of electroplating equipment, andincrease maintenance requirements.

[0010] The specific metal to be electroplated can also complicate theelectroplating process. For example, electroplating of certain metalstypically requires use of a seed layer having a relatively highelectrical resistance. As a consequence, use of the typical plurality ofelectrical wafer contacts (for example, eight discrete contacts) may notprovide adequate uniformity of the plated metal layer on the wafer.Reduction in sizes of such features as vias and trenches also requiresthinner layers having higher resistivity, which in turn may generate ahigh potential drop from the wafer edges to the central part, wherebythe rate of deposition in the central area is significantly reduced.

[0011] Beyond the problems discussed above, there are also otherproblems associated with electroplating reactors. As device sizesdecrease, the need for tighter control over the processing environmentincreases. This includes control over the contaminants that affect theelectroplating process. The moving components of the reactor, which tendto generate such contaminants, should therefore be subject to strictisolation requirements.

[0012] Still further, existing electroplating reactors are oftendifficult to maintain and/or reconfigure for different electroplatingprocesses. Such difficulties must be overcome if an electroplatingreactor design is to be accepted for large-scale manufacturing.

[0013] One drawback associated with copper deposition by electroplatingis the fact that for very small features on microelectronic workpieces(sub 0.1 micron features), copper deposition by electroplating can lackconformity with the side walls of high aspect ratio vias and trenches,and can produce voids in the formed interconnects and plugs (vias). Thisis often due to the non-conformity of the copper seed layer deposited byPVD or CVD. As a result, the seed layer may not be thick enough to carrythe current to the bottom of high aspect ratio features.

[0014] An alternate process for depositing copper onto a microelectronicworkpiece is known as “electroless” plating which is the deposition ofmetals on a catalytic surface from a solution without an external sourceof current. For example, this process can be used as a preliminary stepin preparing plastic articles for conventional electroplating. Aftercleaning and etching, the plastic surface is immersed in solutions thatreact to precipitate a catalytic metal in situ, palladium, for example.First the plastic is placed in an acidic stannous chloride solution,then into a solution of palladium chloride; palladium is reduced to itscatalytic metallic state by the tin. Another way of producing acatalytic surface is to immerse the plastic article in a colloidalsolution of palladium followed by immersion in an accelerator solution.The plastic article thus treated can now be plated with nickel or copperby the electroless method, which forms a conductive surface, which thencan be plated with other metals by a conventional electroplating method.

[0015] Along with the electroplating method, the electroless method alsohas found wide application in the manufacture of semiconductor devices.

[0016] As compared to electroplating, the electroless plating ordeposition is a selective process, which can be realized with very thinseeds or without the use of seeds at all. Since electroless process isnot associated with the use of electric current, the electrolessdeposition results in more uniform coatings in view of the absence ofdiscrete contacts. Electroless deposition can be realized with the useof simple and inexpensive equipment and with a high aspect ratio gapfill.

[0017] Given below are several examples of methods and apparatuses forelectroless deposition, specifically for use in the manufacture ofsemiconductor devices.

[0018] U.S. Pat. No. 5,500,315 issued in 1996 to J. Calvert, et al.discloses an electroless metal plating-catalyst system that overcomesmany of the limitations of prior systems. In one aspect of theinvention, the process comprises the steps of: providing a substratewith one or more chemical groups capable of ligating to an electrolessdeposition catalyst, at least a portion of the chemical groups beingchemically bonded to the substrate; contacting the substrate with theelectroless metal plating catalyst; and contacting the substrate with anelectroless metal plating solution to form a metal deposit on thesubstrate. The chemical groups can be, for example, covalently bonded tothe substrate. In another preferred aspect, the invention provides aprocess for selective electroless metallization, comprising steps ofselectively modifying the reactivity of a substrate to an electrolessmetallization catalyst; contacting the substrate with the electrolessmetallization catalyst; and contacting the substrate with an electrolessmetallization solution to form a selective electroless deposit on thesubstrate. The substrate reactivity can be modified by selectivetreatment of catalyst ligating groups or precursors thereof on thesubstrate, for example by isomerization, photocleavage or othertransformation of the ligating or precursor groups. Such-directmodification enables selective plating in a much more direct andconvenient manner than prior selective plating techniques. Specifically,the aforementioned patent provides selective electroless depositionwithout the use of a photoresist or an adsorption type tin-containingplating catalyst.

[0019] The method described in the above patent includes an electrolesscatalyst system that requires fewer and simpler processing steps incomparison to current Pd/Sn colloid catalyst adsorption based systems;use of more stable and convenient catalysts, including tin-freecatalysts; and improved catalyst adhesion to a substrate allowingplating of more dense initiation and of greater uniformity andselectivity. The invention also provides selective patterning ofsubstrate ligating groups, thereby enabling a selective metal depositwithout the use of a conventional photoresist patterning sequence.

[0020] U.S. Pat. No. 6,309,524 granted to D. Woodruff, et al. in 2001discloses a universal electroplating/electroless reactor for plating ametal onto surfaces of workpieces. An integrated tool for plating aworkpiece comprises a first processing chamber for plating the workpieceusing an electroless deposition process and a second processing chamberfor plating the workpiece using an electroplating process. A robotictransfer mechanism is used that is programmed to transfer a workpiece tothe first processing chamber for electroless deposition thereof and, ina subsequent operation, to transfer the workpiece to the secondprocessing chamber for electroplating thereof.

[0021] It should be noted that a common problem in using bathes, whichis especially true for the electroless deposition process, is thatforeign particles or contaminants will be deposited on the substratesurface of the wafer when transferring the wafers from one bath toanother bath. Another common problem is the exposure of the substratesurface of the wafer to air during the transfer (from bath to bath) cancause the non-wetting of deep and narrow trenches in the surface orsmall (contact) holes in the surface because of electrolyte evaporation.And yet another common problem is that exposure to air may causeoxidation of the catalytic surface that will result in poor catalyticactivity and poor quality metal deposits. This problem becomesespecially troublesome when using materials such as copper that easilyoxidize in air. To produce high quality metal deposits in the submicronrange, therefore, it is more desirable not to transfer the wafer betweenthe processing chambers and to avoid exposing the wafer to air by usinga single bath or processing chamber and moving the different fluids foreach step in the process through the processing chamber.

[0022] The above problems are solved by the system described in U.S.Pat. No. 5,830,805 issued in 1998 to Y. Shacham-Diamand, et al. Thispatent discloses an electroless deposition apparatus and method ofperforming electroless deposition for processing a semiconductor waferthat use a closed processing chamber to subject the wafer to more thanone processing fluid while retaining the wafer within the chamber. Theinvention is useful for manufacturing processes that include depositing,etching, cleaning, rinsing, and/or drying. The processing chamber usedin the preferred embodiment of the apparatus of the above patent is anenclosed container capable of holding one or more semiconductor wafers.A distribution system introduces a first fluid into the chamber forprocessing the wafer and then removes the first fluid from the chamberafter processing the wafer. The distribution system then introduces thenext fluid into the chamber for processing the wafer and then removesthe next fluid from the chamber after processing the wafer. Thisprocedure continues until the manufacturing process finishes. The fluidsused in the present invention depends on the process performed and mayinclude fluids such as Dl water, N₂ for flushing, and electrolyticsolutions comprising reducing agents, complexing agents, or pHadjusters.

[0023] The fluid enters the sealed processing chamber through an inlet,and exits the chamber through an outlet. As the fluid enters theprocessing chamber, the fluid is dispersed across the wafer in a uniformflow. A recirculation system moves the fluid through the processingchamber using a temperature control system, chemical concentrationmonitoring system, pump system, and a filtration system beforere-circulating the fluid back through the processing chamber.

[0024] Additional embodiments include: a rotatingly mounted tubularwafer housing with a wafer mounted on either or both sides of thehousing surface; an inner core mounted inside of the tubular housingwhen mounting a wafer on the inside surface of the housing; and adispersal apparatus for dispersing the fluid in a uniform flow over thewafer. The processing chamber can be provided with a heater and atemperature control system.

[0025] In spite of their advantages, the known electroless processeshave temperature of the working chemical solution as one of the mainparameters. It is known that speed of deposition in an electrolessprocess depends on the temperature in a degree close to exponential. Forexample, in the article published in “Electroless Nickel Plating,Finishing Publications Ltd., 1991, W. Riedel states (page 39 of thearticle) that temperature is the most important of parameters affectingthe deposition rate and that for Ni-P electroless process the depositionrate increases twofold for every 10 degrees of bath temperature.

[0026] Furthermore, for the metal interconnects on the surface of thewafer one of the major requirements is low resistivity. Copper waschosen as the close second best for fulfilling this requirement.However, due to the presence of various additives in the interfacebetween the PVD Cu seeds and ECD [electroplating copper deposition] Cu,resistivity is disproportionally increased as compared to the one inmuch thinner electroless-deposited Cu layer. This phenomenon wasreported by S. Lopatin at AMC, 2001.

[0027] It has been also shown by Y. Lantasov, et al. in“Microelectronics Engineering”, No. 50 (2000), pp. 441-447, FIG. 2, thatresistivity of ELD Cu strongly depends on deposition conditions, andthat at higher temperatures it is possible to obtain a material with lowresistivity.

[0028] However, it is understood that electroless deposition at hightemperatures leads to significant non-uniformities in the depositedlayers. This occurs due to local temperature fluctuations. The higher isthe temperature, the greater are such fluctuations. Stabilization ofelevated temperatures in large volumes of the solution tanks isassociated with the use of complicated temperature control systems andtemperature maintaining systems (seals, thermal insulations, etc.).This, in turn, increases the cost of the equipment and maintenance.

[0029] For the reasons described above, manufacturers of semiconductorequipment prefer to use electroless processes carried out at roomtemperature. Low speeds of deposition are compensated by utilizing amultiple-station deposition equipment with simultaneous operation of anumber of substrates in a number of chambers arranged in series. Suchequipment requires a large production space and dictates the use oflarge volumes of the solutions. Furthermore, an additional space isneeded for the preparation, storage, and post-use treatment of thesolutions. This, in turn, creates environmental problems.

[0030] Another common drawback of existing electroless depositionapparatuses is low speed of deposition, which in general depends on thetype of the deposited material and even in the best case does not exceed100 nm/min, but normally is much lower. For example, for CoWP the speedof deposition can be within the range from 5 nm/min to 10 nm/min.

[0031] In earlier U.S. patent application Ser. No. 103,015 filed on Mar.22, 2002, the applicants have substantially solved the problems ofelectroplating and electroless deposition associated with processes andapparatuses described above. More specifically, the apparatus describedin the aforementioned patent application has a closable chamber that canbe sealed and is capable of withstanding an increased pressure and hightemperature. The chamber contains a substrate holder, that can berotated around a vertical axis, and an edge-grip mechanism inside thesubstrate holder. The deposition chamber has several inlet ports for thesupply of various process liquids, such as deposition solutions, Dlwater for rinsing, etc., and a port for the supply of a gas underpressure. The apparatus is also provided with reservoirs and tanks forprocessing liquids and gases, as well as with a solution heater and acontrol system for controlling temperature and pressure in the chamber.The heater can be located outside the working chamber or built into thesubstrate holder, or both heaters can be used simultaneously. Uniformdeposition is achieved by carrying out the deposition process underpressure and under temperature slightly below the boiling point of thesolution. The solution can be supplied from above via a showerheadformed in the cover, or through the bottom of the chamber. Rinsing orother auxiliary solutions are supplied via a radially moveable chemicaldispensing arm that can be arranged above the substrate parallelthereto.

[0032] Furthermore, the apparatus of aforementioned U.S. patentapplication Ser. No. 103,015 provides uniform heating of the entireworking solution by means of a heater located either outside of thedeposition chamber with heating of the solution on the way to thechamber, or inside the cover of the deposition chamber. The main idea isto maintain the entire volume of the working solution at a uniformtemperature. In general, the temperature can be adjusted, but shouldremain constant and at a relatively high level (e.g., 80 to 90° C.) allthe time. However, although an elevated temperature of the workingsolution leads to essential increase in the productivity of thedeposition process, the process requires constant replacement of theworking solution since high temperature causes rapid thermaldecomposition of the solution. Constant replacement of the solutionshould be carried out with high flow rates, and this, in turn, increasesthe cost of the production.

[0033] The undesired effect of permanent high temperature on the workingsolution can be explained as follows:

[0034] The electroless deposition is a process of reduction of metalions, e.g., cobalt, tungsten, or the like, on the catalytically-activesurface by electrons released during oxidation of a reducing agent(e.g., hypophosphite anions). Oxidation of the reducing agent iscatalyzed by a substrate, and, in the case of the most widely acceptedmodel, it can be assumed that the charge from the reducing agent istransferred to metal ions through the substrate and thus produces metalatoms on the substrate surface.

[0035] A simplified combined chemical reaction for the above process canbe expressed as follows:

H₂PO₂ ⁻+H₂O +Co⁺⁺=CO_(o) +H⁺+H₂PO₃

[0036] The reducing agent is consumed by deposition of metal on theprocessed part, by hydrolysis at high temperature (especially on hotspots of heating elements), by catalytic oxidation on particlesgenerated by the deposition tool hardware, and by a reaction of reducingagent with reactive components (such as ethylene bonds, carboxyl groups,etc.) of the polymers used in tool construction.

[0037] At sufficiently high concentration of contamination particlesand/or at the boiling point of the solution, the composition can bespontaneously and completely decomposed by metal reduction at thesurfaces of the aforementioned particles (and defects). As soon as fewmetal atoms are formed, they become a new nucleation sites for furthercontinuous decomposition of the solution.

[0038] International Patent Application Publication No. WO 02/34962(hereinafter referred to as International Application) disclosed on May2, 2002 describes an electroless apparatus, in which the problem ofthermal decomposition of the working solution is partially solved byutilizing a substrate holder with a heating device. The substrate holderof this apparatus has a substrate chuck for clamping the substrateduring deposition in the working chamber in a position of the treatedsurface facing down.

[0039] The main disadvantage of the apparatus of the aforementionedInternational Application is that the substrate is oriented with thetreated surface facing down. It is known that in a static condition ofthe solution or in processes with low-velocity flows of the solution,the aforementioned orientation of the substrate leads to accumulation ofgas bubbles on the treated surface. The gas bubbles, in turn, violateconditions required for uniformity of deposition. In order to solve thisproblem, in the apparatus of the International Application thedeposition chamber has a curvilinear bottom surface for guiding theflows of the working solution in specific paths over the facing-downsurface of the substrate. However, even though the flows of the workingsolution generate some dynamic conditions on the edge surfaces of thesubstrate, a certain stagnation point will always remain in the centralpart of the substrate. This local area may accumulate gas bubbles.Furthermore, differential of velocities of the flow on the substratesurface may lead to non-uniform temperature distribution. In otherwords, the apparatus of the International Application does not provideuniformity of electroless deposition.

[0040] In order to eliminate problems associated with accumulation ofgas bubbles and stagnation of the solution in the central area of thechuck, one of the embodiments of the aforementioned apparatus includes acomplicated kinematic system with wobbling motions of the rotatingchuck. Such a complicated system makes the apparatus and products moreexpensive, while the process becomes difficult to control.

[0041] The above problem was solved with the use of an electrolessmethod and apparatus disclosed in another earlier U.S. patentapplication Ser. No. 247,895 filed by the same applicants on Oct. 20,2002. More specifically, the above application relates to a method andapparatus for electroless deposition of a coating material, which may bea metal, semiconductor, or dielectric, that is carried out at arelatively low temperature of the working solution compensated by anincreased temperature on the substrate which is controlled by a heaterbuilt into the substrate chuck. A decrease in the temperature of theworking solution prevents thermal decomposition of the solution andreduces formation of gas bubbles, normally generated at increasedtemperatures. Accumulation of bubbles on the surface of the substrate isfurther prevented due to upwardly-facing orientation of the treatedsurface of the substrate. The substrate holder is equipped with asubstrate heater and a substrate cooler, that can be used alternatinglyfor quick heating or cooling of the substrate surface. In addition tothe thermally-controlled substrate holder, the apparatus of theinvention is provided with oscillating nozzles located in the depositionchamber above the treated surface and used for rapid and uniform wettingof the entire treated surface of the substrate at the initial stage offilling of the working chamber with the solution.

[0042] In spite of the advantages provided by the last-mentionedinvention, the method of thermally-controlled electroless depositiondisclosed in the above application does not takes into account thespecificity of the formation of a coating film on various stages of thefilm-growth process and therefore does not use to full extent all thetechnological possibilities of the apparatus disclosed in the aboveapplication.

OBJECTS AND SUMMARY OF THE INVENTION

[0043] It is an object of the present invention to provide a method ofelectroless deposition of very thin films of high uniformity withoutthermal decomposition of the working solution with accurate control ofthe process depending on the condition of the film structure on variousstages of the deposition processing. It is another object is to providea method for electroless deposition with impulse heating and cooling foroptimization of the structure of the film obtained in various stages ofthe deposition. Still another object is to provide a method forelectroless deposition with the most efficient use of anelectroless-deposition apparatus that allows instantaneous heating andcooling of the substrate. A further object is to provide a method thatresults in the formation of thin deposition films of high uniformity andof the highest quality.

[0044] The method of the invention comprises accumulating experimentaldata or obtaining existing data with regard to the optimaltime-temperature relationship of the deposition process on variousfilm-formation stages for various materials, forming nuclei of aselected material on the surface of the treated object in the firststage under first temperature-controlled conditions for the formation ofnuclei of said selected material, converting the nuclei of theaforementioned selected material into island-structured deposited layerof said material by causing lateral growth of the nuclei under secondtemperature-controlled conditions; converting the island-structure layerinto a continuously interconnected cluster structure by causing furtherlateral growth of said island-structured deposited layer under thirdtemperature-controlled conditions; forming a first continuous film ofsaid material under fourth temperature controlled conditions whichprovides said first continuous film with predetermined properties; andthen completing the formation of a final coating film by growing atleast one subsequent continuous film of said material under fifthtemperature-controlled conditions until a film of a predeterminedthickness is obtained. The fifth temperature-controlled conditions maybe characterized by a pulse-mode or step-like variations of temperaturein time with rapid cooling or heating for obtaining high degree ofcrystallinity or for increase in the rate of deposition. The method ofthe invention could be realized with the use of the electrolessdeposition apparatus with instantaneous cooling or heating of theobject, e.g., a semiconductor substrate, in a deposition chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045]FIG. 1 is a schematic vertical cross-sectional view of anelectroless deposition apparatus suitable for carrying out a method ofthe invention.

[0046]FIG. 2 is a sectional view of a substrate holder used in theapparatus of FIG. 1. FIG. 3A is a graph illustrating an example ofdeposition of copper onto a cobalt layer on a dielectric substrate bythe method of the invention with variations of the substrate temperaturein time.

[0047]FIG. 3B is a graph similar to FIG. 3A illustrating application ofthe method of the invention for deposition of a CoWP barrier layer ontoa dielectric substrate.

[0048]FIG. 4 is a graph illustrating measured variations of electricalpotential on the surface of a layer growing during electrolessdeposition of CoWP onto a copper plate.

[0049]FIG. 5 is a time-temperature relationship illustrating thedeposition process of the invention with control of structures inindividual layers of a multiple-layered coating film.

[0050]FIG. 6 illustrates a process of the invention for the formation ofa multiple-layered structure, wherein individual layers of the coatingfilm are formed from different deposition materials of a metal ornon-metal nature.

DETAILED DESCRIPTION OF THE INVENTION

[0051] For better understanding the principle of the invention, let usfirst consider in some detail a mechanism of film formation inelectroless deposition process.

[0052] Formation of thin films in electroless deposition, which in factcan be classified as a heterophasal (solid and liquid phases) epithaxy(LPD) and in a gaseous phase epithaxy (CVD, MOCVD, etc.), havesimilarity from the point of view of the film formation mechanisms (seePhysical Chemistry of Surfaces, Fifth edition, by Arthur W. Adamson,John Wiley & Sons, Inc. Publishers, 1990, pp. 421-459).

[0053] Although a majority of publications available in the literaturerelates mostly to analysis of deposition from a gas phase, and muchfewer works are dedicated to processes of deposition from a liquidphase, the available information is sufficient for understanding mainmechanisms acting during the formation of thin films by deposition froma liquid phase. More specifically, the film-growth process can becharacterized by three main mechanisms of growth, which can becharacterized by an energetic parameter γ(γ=σ_(fl)+σ_(fs)−σ_(sl), whereσ_(fl) is a specific surface energy on the film-liquid interface, σ_(fs)is a specific surface energy on the film-substrate interface, and σ_(sl)is a specific surface energy on the substrate-liquid interface).

[0054] If γ is less than 0, i.e., in the case of strong interactionbetween the film and the substrate, the film is growing in alayer-by-layer manner. Each layer is formed with lateral growth oftwo-dimensional nuclei spreading over the surface of the precedinglayer. Such mechanism is typical in the deposition of a metal film ontoa metal surface. The first-layer film may be preliminarily formed on anon-metal substrate, e.g., on a silicon oxide layer. The subsequentlayers will then grow as described above. In addition to γ<0, theheteroepithaxial growth requires at least approximate match betweencrystalline lattices of the substrate and the material of the depositedfilm.

[0055] If the interaction between the film and the substrate is weak(γ>0), the first stage of the film growth constitutes formation ofisolated “islands” of the deposited material. Further growth of theseislands leads to the formation of a continuous coating layer. Theaforementioned island-formation mechanism, which is also known as theVolmer-Weber mechanism, occurs in the formation of coating films frommetals with high energy of cohesion, such Ag, Au, Cu, Ni, on substrateswith low energy of cohesion, such as glass, silicon oxide, etc.

[0056] There can be an intermediate case when the energetic conditionsof the process causes growth of the film in a layer-by-layer manner, andafter the formation of one or more highly-stressed layers the continuityof the film is violated and further growth of the film continues in anisland pattern. Such mechanism often occurs in some practicallyimportant systems with deposition of metal onto metal or metal ontosemiconductor.

[0057] Thus, depositions of films from a liquid phase onto a solidsubstrate pass through a number of sequential stages which arecharacterized by specific features, i.e., after a short-term period offormation of nuclei, the growth is converted into an island-formationstage. In the island-formation stage, the islands grow as a certainstatistical ensemble of interacting objects subordinate to a specificstatistical law. This stage determines the structure of the future filmand hence the film properties.

[0058] The next step in the film-growth mechanism is formation of acontinuous cluster structure composed of interconnected islands. Thisstage designates transition from the isolated-island structure to acontinuous structure electrically conductive for metal films. The abovetransition occurs very rapidly and in fact is a percolation transitionin a two-dimensional system of randomly-arranged elements.

[0059] In the cluster-formation stage, film-growth tendencies,morphology, and physical properties of the growing film could beunderstood by considering the film as a random two-dimensional lattice.It is understood that the cluster-formation stage continues until acontinuous film is formed. At the end of the cluster-formation stage,the film acquires a structure interweaved with a labyrinth of microporeswhich may determine the microrelief of the continuous films formed onthe subsequent stages.

[0060] It is understood that different stages have different kinetics ofthe process. As has been mentioned above (see, e.g., Y. Lantasov, et al.in “Microelectronics Engineering”, No. 50 (2000), pp. 441-447), byvarying parameters of a liquid heterophaseous, it becomes possible tocontrol a degree of crystallization in the deposited films. Probably,with this approach it would be possible to obtain films with structuresin a wide range from fully amorphous to strictly crystalline. Such filmswith high degree of crystallization are most valuable from the practicalpoint of view due to high stability of their properties. Therefore, inthe formation of coating films, it would be advantageous to maintainfilm-growth conditions that would provide high-degree of crystallizationin the deposited films.

[0061] The above considerations can be summarized as follows:

[0062] 1) A process of liquid heterophaseous epithaxial growth of filmscan be roughly divided into several stages with specific mechanisms ofgrowth.

[0063] 2) Durations and film-growth rates may be significantly differentin different stages, sometimes with a factor of 100.

[0064] 3) Each stage has its own optimal conditions which may be notoptimal in other stages.

[0065] 4) In order to obtain coating films with controlled and highestcharacteristics and properties (such as dispersivity, crystallinity,spatial stoicheometric uniformity, thickness uniformity, etc.), thefilm-formation process should be optimized individually in each specificstage of this process with reference to the specific conditions of thisprocess.

[0066] The method of the invention comprises accumulating experimentaldata or obtaining existing data with regard to the optimaltime-temperature relationship of the deposition process on variousfilm-formation stages for various materials, forming nuclei of aselected material on the surface of the treated object in the firststage under first temperature-controlled conditions for the formation ofnuclei of said selected material, converting the nuclei of theaforementioned selected material into island-structured deposited layerof said material by causing lateral growth of the nuclei under secondtemperature-controlled conditions; converting the island-structure layerinto a continuously interconnected cluster structure by causing furtherlateral growth of said island-structured deposited layer under thirdtemperature-controlled conditions; forming a first continuous film ofsaid material under fourth temperature controlled conditions whichprovides said first continuous film with predetermined properties; andthen completing the formation of a final coating film by growing atleast one subsequent continuous film of said material under fifthtemperature-controlled conditions until a film of a predeterminedthickness is obtained. The fifth temperature-controlled conditions maybe characterized by a pulse-mode or step-like variations of temperaturein time with rapid cooling or heating for obtaining high degree ofcrystallinity or for increase in the rate of deposition. The method ofthe invention could be realized with the use of the electrolessdeposition apparatus with instantaneous cooling or heating of theobject, e.g., a semiconductor substrate, in a deposition chamber.

[0067] In the context of the present invention, the term “instantaneous”means time required for changing the temperature of a treated object,e.g., a semiconductor substrate. In an electroless deposition process,such instantaneous change may occur during a time interval fromfractions of a second to several seconds. As compared to the total timeof the process (up to several minutes), the heating or cooling forfractions of seconds may be considered very rapid or instantaneous.

[0068] The apparatus for realization of the method is beyond the scopeof the present invention and is described in aforementioned earlier U.S.patent application Ser. No. 247,895.

[0069] For description of the method, it would be advantageous first toconsider the structure of the aforementioned apparatus, which isincorporated herein as a reference.

[0070]FIG. 1 is a schematic vertical cross-sectional view of anelectroless deposition apparatus 20. Only those parts and units of thisapparatus will be described in this application. The apparatus 20 has asealable working chamber 22 which has a lower cup-shaped part 22 a withan open part facing upward and a moveable upper cup-shaped part 22 bwith its open facing down towards the opening of the lower part 22 a. Ina closed state shown in FIG. 1, both parts 22 a and 22 b of the workingchamber 22 form a sealed space 22 c.

[0071] Reference numeral 25 a designates a first gas supply pipe, andreference numeral 25 b designates a pressure control valve forcontrolling gas pressure inside the sealed space 22 c.

[0072] Reference numeral 27 a designates a fluid supply pipe equippedwith a three-way valve 27 b for selective supply of a working solution,water, or gas into the sealed space 22 c. For this purpose, the valve 27b is connected to a working-solution supply pipe 27 c, a water supplypipe 27 d, and a gas supply pipe 27 e. The pipe 27 e may be used for thesupply of air or a neutral gas such as dried nitrogen.

[0073] Located in the sealed space 22 c is a disk-like substrate holder24 with a central recess 26 having diameter D1 smaller than the diameterD2 of a substrate W. The holder 20 is rotated by means of a shaft 28,which may have the same construction and can be driven from the samedrive mechanisms as described in aforementioned U.S. patent applicationSer. No. 103,015.

[0074] The holder 24 can be provided with an edge-grip mechanism 30,which may be of the same type as disclosed in aforementioned U.S. patentapplication Ser. No. 103,015.

[0075] The recess 26 has a recess inlet channel 32, which is formedinside the rotating shaft 28, e.g., along the central line of the shaft28. The recess also has an outlet channel 34. Since the substrate holder24 rotates, while the outlet channel is stationary, in FIG. 1 thepassage 34 is shown conventionally, and connections between the moveableand stationary parts of the outlet unit are not shown. A tank 38 thatcontains a heating/cooling medium is connected to a small pump 38 bwhich may be required for decrease of gas pressure in the tank 38.Reference numeral 38 a designates a tank temperature control unit, e.g.,a thermocouple.

[0076] The outlet channel 34 is connected to the cooling/heating liquidtank 38 by a pipe 36. Reference numeral 40 designates a cut-off valve.The inlet channel 32 is connected to a pipe 51, which links the channel32 to the heater 46 or the cooler 48 via the two-way valve 44. The tank38 is equipped with a stirrer 42.

[0077] The recess inlet channel 32 is connected to a two-way valve 44and can be selectively connected to the heating/cooling liquid tank 38via a heater 46 or a cooler 48. A pipe 50 branched from the recess inletchannel 32 is connected to a pressure differential control unit 52intended for controlling a pressure ratio between the pressure of theworking solution in the working chamber 22 and the pressure of theheating/cooling medium in the recess 26. The control unit 52 is amembrane-type device that has a membrane 54 with strain gages 54 a and54 b which convert deformations of the membrane 54 into electricalsignals sent to a controller 56. The control 56, in turn, is connectedto actuating mechanisms (not shown) of the two-way valve 44, the heater46, the cooler 48, the strain gages 54 a, 54 b, the thermocouple 38 a,the pump 38 b, and the control valve 25 b.

[0078] Reference numeral 58 designates a solution return line with avalve for returning the working solution to the main reservoir of theelectroless deposition apparatus (not shown in the present applicationbut illustrated in U.S. patent application Ser. No. 103015 filed by thesame applicant in 2002).

[0079]FIG. 2 illustrates a substrate holder 124 made in accordance withanother embodiment of the invention. The substrate holder 124 of thisembodiment differs from the substrate holder 24 of the embodiment ofFIG. 1 by the absence of the edge grippers 30. The upper end face 121 ofthe substrate holder 124 has a shallow tapered boring 125, which forms aseat for the substrate W1. The diameter D3 on the bottom of the boring125 is equal to or slightly greater than the diameter D4 of the waferW1, so that the wafer W1 can be placed into and centered in the boring125. The rest of the construction of the substrate holder 120 is thesame as that of the substrate holder of FIG. 1.

[0080] When the substrate W1 is placed into the boring 125, thepressures above the substrate, i.e., in the working chamber, isincreased to a level slightly higher than the pressure inside the recess126 and is sufficient for securing the substrate W1 on its seat and forsealing the heating/cooling recess 126.

[0081] It is understood that in this and in all other embodiments of theinvention, the substrate holder is equipped with the substratelifting/descending mechanism (not show in this application) of the typeshown in aforementioned U.S. patent application Ser. No. 103,015 andintended for loading of the substrate W into the substrate holder andfor lifting it prior to unloading.

[0082] It is understood that since the wafer W1 itself forms a wall ofthe recess 126 for the cooling/heating liquid, the substrate holder 24(124) shown in FIGS. 1 and 2 provides instant cooling or heating of thesubstrate, i.e., possesses the feature required for accomplishing themethod of the present invention.

[0083] More specifically, the method of the invention comprises forminga multiple-layered coating on a substrate, where the aforementionedlayers have different structures. These structures are controlled bycontrolling temperatures of the processes in the stages of the formationof different layers by supplying to the recess 26 (126) a cooling orheating liquid and by controlling the speed of cooling or heating of theliquid, and hence of the wafer or substrate, which is always maintainedin direct contact with the cooling/heating liquid. As heating andcooling can be performed without inertia, i.e., almost instantaneously,the apparatus allows heating or cooling in a pulse mode unattainablewith apparatus of other known types. For example, instantaneous coolingmakes it possible to form in the film layer of a high-qualitycrystalline structure. In principle, the method of the invention makesit possible to form crystalline, as well as purely amorphous orpartially crystalline structures.

[0084] The method of the invention can be performed more efficientlywith a provision of a preliminarily-accumulated experimental data withregard to the optimal time-temperature relationship of the depositionprocess in various film-formation stages for various materials. Forexample, such stages may comprise forming nuclei of a selected materialon the surface of the treated object in the first period of depositionunder first temperature-controlled conditions for the formation ofnuclei of the selected material, converting the nuclei into anisland-structured deposited layer of the material by causing lateralgrowth of the nuclei under second temperature-controlled conditions,converting the island-structure layer into a continuously interconnectedcluster structure by causing further lateral growth of theisland-structured deposited layer under third temperature-controlledconditions, forming a first continuous film of the material under fourthtemperature controlled conditions which provide the first continuousfilm with predetermined properties, and then completing the formation ofa final coating film by growing at least one subsequent continuous filmof the material under fifth temperature-controlled conditions until afilm of a predetermined thickness is obtained. The fifthtemperature-controlled condition may be characterized by a pulse-mode orstep-like variations of temperature in time with rapid cooling orheating for obtaining high degree of crystallinity or for increase inthe rate of deposition.

OPERATION OF THE APPARATUS AND DESCRIPTION OF THE METHOD

[0085] In order to prevent formation of gas bubbles in the recess 26under a substrate W, prior to placement of the substrate into thesubstrate holder 20, the latter is first filled with a liquid, e.g.,with the cooling or heating liquid (depending on the selected mode ofmetal deposition an the structure of the deposited layer) to the levelexceeding the upper edge of the recess 26, and only after that thesubstrate is placed into the holder 20 and, if necessary, is clamped inthe holder 20 (FIG. 1). The working chamber 22 is then filled with theworking solution. The deposition process is carried out by precipitationof the coating material from the working solution, while the temperatureon the surface of the substrate W is controlled by continuing the supplyof the heating/cooling medium to the recess 26 (126). (FIGS. 1 and 2).The liquid is uniformly removed from the recess 26 (126) through themedium return line 58.

[0086] In order to ensure balance of the pressure inside the recess 26(126), pressure developed in the working chamber above the substrate W(FIG. 1) can be adjusted by means of gas supplied, e.g., through the gassupply line 25 a (FIG. 1), to a value equal to or slightly exceeding thepressure of liquid in the recess 26 (326) on the back side of thesubstrate W. The pressure in the recess is controlled by the pressuredifferential control unit 52 (FIG. 1) equipped with the strain gages 54a and 54 b which convert deformations of the membrane 54 into electricalsignals sent to a controller 56. The controller 56, in turn, isconnected to actuating mechanisms (not shown) of the two-way valve 44,the heater 46, the cooler 48, the strain gages 54 a, 54 b, thethermocouple 38 a, the pump 38 b, and the control valve 25 b. During theoperation, the pressure of the working solution in the working chamber22 above the substrate W is always maintained at a level slightly higherthan the pressure inside the recess. This allows performing fixation ofthe substrate W in the substrate holder 20 without the use of a clampingmechanism, if the holder corresponds to the embodiment shown in FIG. 2.

[0087] Given below are several examples of different multiple-layersstructures described with reference to graphs illustrating control ofthe substrate temperature on different stages of the film growth.

[0088]FIG. 3A is a graph illustrating an example of a deposition ofcopper onto a dielectric substrate with variations of the substratetemperature in time. The time t (sec.) is plotted on the abscissa axis,and the temperature T (°C.) is plotted on the ordinate axis. The graphof FIG. 3A describes a complete cycle from initiation of the electrolessdeposition process till the formation of a continuous coating film of apredetermined thickness. The applicant studied and measured variationsof electrical potential on the surface of a layer growing duringelectroless deposition of CoWP onto a copper layer formed on adielectric plate. An example of such measurements is shown in FIG. 4. Inthis graph, the electrical potential is plotted on the ordinate axis,and the time is plotted on the abscissa axis. Three curves shown in thisgraph relate to three slightly different temperatures of deposition. Thecurves make it possible to identify different stages of the depositionprocess. More specifically, the 72° C. curve consists of threedistinctly different sections, wherein sections I-II relate to thenucleus and island formation stage. On the section II the potentialinstantaneously drops to the lowest level. This stage corresponds to thecompletion of the percolation stage when all the islands becomeelectrically connected into a conductive structure and the intermediatespaces between the islands are filled. In other words, the formation ofa continuous film is completed approximately 80 sec. from the beginningof the process. Section III corresponds to the stage with the constantpotential, when the growth of the film is continued to a predeterminedthickness. Normally, sections I and II are known as the initial periodof the film formation (stages of formation of nuclei, islands, and thefirst continuous layer), and the time corresponding to the above periodis called Initiation time. It is clearly seen that transfer from 78° C.to 75° C. and then to 72° C. changes the initiation time from 80 sec. to35 sec. and then to 8 sec., respectively.

[0089] Looking at the graphs of FIG. 4, one can think that the structurecan be easily adjusted merely by increasing the process temperature: thehigher is the temperature, the shorter is the initiation time, and thehigher is efficiency of the process. However, in reality the film growthprocess is more complicated since during the aforementioned initial timethe deposition grows not only in the lateral direction but also in thedirection perpendicular to the plane of the substrate. As a result, thenuclei may grow significantly in a vertical direction so that theinitial continuous layer may have significant surface roughness. Thisinitial roughness will be reproduced in the subsequent layer, and eventhe final layer will reflect this roughness and will have a noticeableH_(RMS) (the height of microroughnesses on the surface of the film). Themethod of the invention is aimed particularly at the selection of suchtemperatures and time intervals in different deposition stages forspecific materials of the substrate and deposition materials, whichprovide the minimal rate of growth in the vertical direction and themaximal rate of growth in the lateral direction.

[0090] Kinetics similar to the one observed in FIG. 4 can also benotices in the growth of copper on a cobalt layer. Although it isunderstood that in each specific case, the initial time of filmformation and the time required for the formation of the basic film willdepend on such factors as composition, concentration, pH and othercharacteristics of the working solution, in both cases, variations ofelectrical potential on the surface of a layer growing duringelectroless deposition will be approximately the same.

[0091] Referring back to FIG. 3A, for the case of deposition of Cu ontoan activated cobalt layer, the time interval from 0 to t₁ is the oneduring which the initial process temperature, e.g., 20° C., isestablished. The time interval from t₁ to t₂ may constitute a nucleusformation period, which normally lasts a few seconds. The time intervalfrom t₂ to t₃ is a period during which islands are formed and connectedinto clusters. This period may last about 25 sec. In the illustratedcase, the temperature instantaneously grows to a value of 70° C., whichwas selected from the graphs of FIG. 4 as the most optimal temperature.In the subsequent period from moment t₃ to moment t₄, which may requirefrom 30 to 60 sec., the temperature may be raised to 95° C. for growthof the film to a required thickness. The process described above makesit possible to grow films having thickness from 250 to 400 Å, andgreater.

[0092]FIG. 3B is a graph similar to FIG. 3A illustrating application ofthe method of the invention for deposition of a CoWP barrier layer ontoa dielectric substrate. It is known that an amorphous structure is theone preferably for a barrier layer. It is also known that amorphousstructures are formed at relatively low temperatures. This condition isreflected in FIG. 3B where the initial period of deposition (t₂ to t₃)occurs at relatively high temperatures (about 90° C. in the example ofFIG. 3B), while the amorphous layer is formed at about 70° C. Suchsequential formation of a basic copper layer over a preliminarily formedbarrier layer can be realized with especially high efficiency if bothlayers are grown in the same single-wafer processing chamber.

[0093]FIG. 5 is a time-temperature relationship illustrating thedeposition process with control of structures in individual layers of amultiple-layered coating film. More specifically, the aforementionedindividual layers have different structures. The initial continuouscoating layer is shown with the same periods and stages of the filmformation (period from 0 to t₃) as in FIG. 3A. The subsequent stagesfrom t₃ to t₄ correspond to a pulse mode of film growth with temperaturepulses having different amplitudes A₁, A₂, A₃ and different durations oftime intervals between the temperature pulses. In other words, theprocess of the type shown in FIG. 5 makes it possible to obtain acoating film of a laminated structure with different thicknesses andstructures of individual layers. For example, the layers may beseparated by sublayers (formed during intervals t₄ to t₅ and t₆ to t₇)having the same stoichometry but different degrees and nature ofcrystallinity.

[0094]FIG. 6 illustrates a process of formation of a multiple-layeredstructure, wherein individual layers of the coating film are formed fromdifferent deposition materials of a metal or non-metal nature. Ingeneral, the graph is similar to the one shown in FIG. 5, but differsfrom it by inclusion of a cleaning period between the deposition ofdifferent materials. These cleaning period from t_(cl1) to t_(cl2) isneeded for replacement of the deposition solution in the sealableworking chamber 22 (FIG. 1). It is understood that during cleaning thesubstrate is maintained at T_(cl) temperature required for optimizationof cleaning. After complete removal of the residue of the firstdeposition solution, a new deposition solution is supplied to thesealable working chamber during period from t₇ and t_(cl2). It isunderstood that during deposition of a new material from the newsolution during period from t₇ to t₁₂ (FIG. 6), the initial depositedfilm functions as a substrate. It is also understood that all optimaltemperatures and time intervals will be different from those fordeposition of the first layer. It can be seen that the second layer isdeposited with a pulse mode of temperature variation.

[0095] Thus it has been shown that the present invention provides amethod of electroless deposition of very thin films of high uniformitywithout thermal decomposition of the working solution and with accuratecontrol of the process depending on the condition of the film structureon various stages of the deposition processing. The method is suitablefor electroless deposition with impulse heating and cooling foroptimization of the structure of the film obtained in various stages ofthe deposition. The method can be carried out with the use of anelectroless-deposition apparatus that allows instantaneous heating andcooling of the substrate and produces thin deposition films of highuniformity and of the highest quality.

[0096] The invention has been shown and described with reference tospecific embodiments, which should be construed only as examples and donot limit the scope of practical applications of the invention.Therefore any changes and modifications in technological processes,constructions, materials, shapes, and their components are possible,provided these changes and modifications do not depart from the scope ofthe patent claims. For example, the process can be carried out in anyother processing apparatus that provides instantaneous heating/cooling.The temperature-versus-time graphs should be considered as illustrativeand the temperature pulses, their amplitudes, and durations my bedifferent. The layers may be formed from metals or non-metals, fromcrystalline an amorphous materials. The coating films may have amultiple-layered structure composed of various materials and theircombinations. The films may have different thicknesses. Although theterm “structure” was used as a distinguishing feature of each individuallayer, it is understood that this term should be construed as“characteristic” of the layer, since the method of the invention makesit possible to change not only the physical structure but alsoelectrical characteristics or the like.

1. A method of forming a film of at least one deposition material on anobject in an electroless deposition process from a deposition solution,said film having a predetermined thickness and characteristics dependenton the temperature of said object during obtaining of saidcharacteristics, said method comprising: providing an electrolessdeposition apparatus having means for instantaneous control oftemperature of said object during obtaining of said characteristics;dividing said electroless deposition process into at least two processstages characterized by specific optimal parameters of growth of saidfilm; and carrying out a deposition process of said deposition materialwhile maintaining said object during each one of said process stages attemperatures changed under conditions of said instantaneous control forobtaining said specific optimal parameters.
 2. The method of claim 1,wherein said characteristics comprise the structure of said film.
 3. Themethod of claim 2, wherein said object is a semiconductor substrate. 4.The method of claim 3, wherein said at least two process stagescomprise: depositing said deposition material in an initial stage, inwhich a first continuous layer of said deposition material is formed onsaid semiconductor substrate, and depositing said deposition material ina first main stage of the growth of at least one main layer formed onsaid first continuous layer.
 5. The method of claim 4, comprising thesteps of depositing a plurality of main layers having differentcharacteristics onto said at least one main layer, each one of saidplurality of main layers being deposited at temperatures changed underconditions of said instantaneous control for obtaining said differentcharacteristics.
 6. The method of claim 5, wherein said differentcharacteristics are different structures.
 7. The method of claim 1,comprising the step of forming said film with a multiple-layeredstructure comprising a plurality of individual layers formed fromdifferent deposition materials.
 8. The method of claim 7, wherein ineach one of said individual layers said characteristics comprise thestructure of each one of said individual layers.
 9. The method of claim8, wherein said object is a semiconductor substrate.
 10. The method ofclaim 9, comprising the steps of forming each one of said multiplelayers in least two process stages comprise an initial stage, in which afirst continuous layer of said deposition material is formed on saidsemiconductor substrate, and a main stage of the growth of each one ofsaid individual layers on said first continuous layer.
 11. The method ofclaim 10, comprising the step of depositing each one of said pluralityof main at temperatures changed under conditions of said instantaneouscontrol for obtaining said different characteristics.
 12. The method ofclaim 7, comprising the step of providing a cleaning stage performedbetween forming said individual layers for replacing said depositionsolution.
 13. The method of claim 11, comprising the step of providing acleaning stage performed for replacing said deposition solution at acleaning temperature between forming said individual layers.
 14. Themethod of claim 8, wherein said structure of each one of said individuallayers is selected from a group consisting of a crystalline and anamorphous structure.
 15. The method of claim 1, wherein saidinstantaneous control of temperature comprises the step of changing thetemperature of said object during period of time ranging from fractionsof a second to several seconds.
 16. The method of claim 4, wherein saidinstantaneous control of temperature comprises the step of changing thetemperature of said object during period of time ranging from fractionsof a second to several seconds.
 17. The method of claim 7, wherein saidinstantaneous control of temperature comprises the step of changing thetemperature of said object during period of time ranging from fractionsof a second to several seconds.
 18. The method of claim 4, wherein saidstep of depositing said deposition material in a first main stage of thegrowth of at least one main layer formed on said first continuous layeris carried out with changes of the temperature of said object in pulsemode.
 19. The method of claim 10, wherein a main stage of the growth ofeach one of said individual layers is carried out with variation of thetemperature of said substrate in a pulse mode.
 20. A method of forming afilm of at least one deposition material on a semiconductor substrate inan electroless deposition process from a deposition solution, saidmethod comprising the steps of: accumulating experimental data withregard to the optimal time-temperature relationship of the depositionprocess on various film-formation stages for a plurality of materials;forming nuclei of a selected material from said plurality of materialson the surface of said semiconductor substrate in the first stage underfirst temperature-controlled conditions and during a first period oftime for the formation of nuclei of said selected material; convertingsaid nuclei of said selected material into an island structure during asecond period of time and under second temperature-controlled conditionsat which are growing substantially in a lateral direction parallel tosaid semiconductor substrate and have a limited growth in the directionperpendicular to said substrate; converting said island structure into acontinuously interconnected cluster structure by causing further lateralgrowth of said island structure under third temperature-controlledconditions; forming a first continuous layer of said deposition materialunder fourth temperature controlled conditions which provides said firstcontinuous layer with predetermined properties; and then completing theformation of a final coating layer by growing at least one subsequentcontinuous layer of said material under fifth temperature-controlledconditions until a film of a predetermined thickness is obtained. 21.The method of claim 20, wherein said instantaneous control oftemperature comprises the step of changing the temperature of saidobject during period of time ranging from fractions of a second toseveral seconds.